When we see records being broken and unprecedented events such as this, the onus is on those who deny any connection to climate change to prove their case. Global warming has fundamentally altered the background conditions that give rise to all weather. In the strictest sense, all weather is now connected to climate change. Kevin Trenberth

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Tuesday, April 29, 2008

As oil prices soared to record levels in recent years, basic economics suggested that consumption would fall and supply would rise as producers opened the taps to pump more.

But as prices flirt with $120 a barrel, many energy specialists are becoming worried that neither seems to be happening. Higher prices have done little to attract new production or to suppress global demand, and the resulting mismatch has sent oil prices spiraling upward.

A central reason supply is not rising to meet demand is that producers outside of the OPEC cartel -- countries like Russia, Mexico and Norway -- have been showing troubling signs of sluggishness. Unlike the Organization of Petroleum Exporting Countries, whose explicit goal is to regulate supply to keep prices up, the other countries are the free traders of the international market, with every incentive to produce flat-out at a time of high prices.

That they are not doing so is a troubling sign. Countries outside of OPEC have been the main source of production growth in the past three decades, as new fields were discovered in Alaska, the North Sea or West Africa. After the collapse of the Soviet Union, new opportunities emerged in Russia and the Caspian Sea.

But for a variety of reasons, including sharply higher drilling costs and nationalistic policies that restrict foreign investments, these countries are finding it difficult, if not impossible, to bolster output. They seem stuck at about 50 million barrels of oil a day, or 60 percent of the world's oil supplies, with few prospects for growth.

Analysts at Barclays Capital said last week that non-OPEC supplies were "seemingly dead in the water." Goldman Sachs raised similar concerns last month, saying that growth in non-OPEC supplies "can no longer be taken for granted."

At the same time, oil consumption keeps expanding at a faster clip than production. Demand is forecast to increase this year by 1.2 million barrels a day, to 87.2 million barrels a day. Consumption has actually fallen a bit in the United States, the world's biggest consumer, as the country grapples with an economic slowdown.

But that drop is being offset by growth in other countries. World consumption is projected to rise 35 percent, to around 115 million barrels a day, in the next two decades. Most of the growth will come from China, India and oil-producing countries in the Middle East, where retail fuel prices are subsidized, encouraging wasteful consumption.

"What is disturbing here is that things seem to get worse, not better," an analyst at Goldman Sachs, David Greely, said. "These high prices are not attracting meaningful new supplies."

Oil for June delivery settled at $118.75 a barrel Monday on the New York Mercantile Exchange after earlier touching a record $119.93. Longer-term oil futures, dated for 2013, now trade at $108 a barrel, a strong indication that investors see little cause for prices to drop in the next five years - partly because of low expectations about production growth.

The outlook for oil supplies "signals a period of unprecedented scarcity," an analyst at CIBC World Markets, Jeff Rubin, said last week.

Oil prices might reach more than $200 by 2012, he said, a level that would probably mean $7 a gallon, or $1.85 a liter, gasoline in the United States.

Some regions are simply running out of reserves. Norway's production has slumped by 25 percent since its peak in 2001. In Britain, the fall has been a more drastic 43 percent drop in eight years. The North Sea is now considered a dying oil basin. The giant field at Prudhoe Bay in Alaska has undergone a similar decline.

In many other places, the problems are not located below ground, as energy executives like to put it, but above ground. Higher petroleum taxes and tougher contract rules, scarce manpower and swelling costs, as well as political wrangling and violence, are making it much harder to bolster production.

"It's a crunch," said J. Robinson West, chairman of PFC Energy, an energy consulting firm in Washington. "The world is not running out of oil, but rather it's running out of oil production capacity."

Recently, the case that has attracted the most attention is Mexico, a leading exporter to the United States, which seems increasingly helpless to stem the collapse of its largest oil field, Cantarell. Last week, the country's state-owned oil company, Pemex, said that production had fallen 300,000 barrels a day so far this year, a stunning drop. Mexico's output has dropped 9 percent in two years, and analysts say they expect further declines this year.

A combination of falling production and rising domestic consumption could wipe out Mexico's exports within five years, including the 1.5 million barrels it sends to the United States each day.

Another country, Russia, is also troubling analysts' forecasts. The country is not exactly running out of places to look for oil - a huge part of Eastern Siberia remains unexplored - and Russia has been the biggest contributor to the growth in energy supplies in the last decade.

But this month, Russian energy officials warned that the days of stunning growth that followed the demise of the Soviet Union were over, as the country would focus on stabilizing its output. Russia today produces about 10 million barrels of oil a day, up from a low point of 6 million barrels in 1996.

About 75 percent of the world's oil reserves are in OPEC countries, where governments voluntarily restrict their output to push up prices. As countries like Russia slow output, analysts say OPEC will have to pick up the slack. The oil cartel currently accounts for 40 percent of the world's oil exports.

Further clouding the picture, Saudi Arabia, the world's top oil exporter, signaled last week that it might have trouble increasing its production.

Saudi Arabia, the de facto leader of OPEC, signaled it would freeze any further expansion after next year. That dims the long-range outlook for OPEC supplies, though in the near term, Saudi Arabia is expected to loom larger in the market as it completes a $50 billion plan to increase its capacity to 12.5 million barrels a day. Yet that leaves it well short of the 15 million barrels that most experts say they expected the kingdom to produce in the long run.

OPEC's 13 members say they plan to spend $150 billion to expand capacity by five million barrels a day by 2012, according to estimates by the cartel. But that also falls short of most projections that say OPEC will need to pump 60 million barrels a day by 2030, up from around 36 million barrels a day today, to meet the planned growth in demand.

Reaching that level is going to be impossible unless the violence and tensions in both Iran and Iraq are resolved, analysts said. Because of sanctions for the past 30 years, both countries have been producing much less than their huge oil reserves would permit.

Not everyone has a pessimistic outlook. The U.S. Energy Department forecasts sustained growth in non-OPEC supplies this year and next. A study by the National Petroleum Council, an industry group that provides advice to the secretary of energy, outlined a variety of possibilities for oil expansion, and concluded that the world still had plenty of petroleum resources that could be tapped.

In fact, high prices have sparked a global dash for oil. Companies are trawling deep oceans or seeking to drill in the Arctic Ocean. In some cases, the hunt has been successful. Brazil, for example, has struck large offshore discoveries that could turn the country into one of the world's top 10 producers in the coming decade. Yet it takes years to bring such remote fields into production, and the market needs oil now.

To make up the shortfall, the world is increasingly turning to fuels made from unconventional sources, like biofuels or heavy oil. Canadian tar sands, for example, have attracted large investments, and biofuels have accounted for much of the growth in fuel supplies in the last two years.

The International Energy Agency, an adviser to industrialized countries, estimates that current investments will be insufficient to replace declining oil production, let alone increase overall output. The energy agency said it would take $5.4 trillion by 2030 to bolster global output, a level of investment that is unlikely to be met. It said a crisis "involving an abrupt run-up in prices" could not be ruled out before 2015.

"According to normal economic theory, and the history of oil, rising prices have two major effects: they reduce demand and they induce oil supplies," said Fatih Birol, the chief economist at the energy agency. "Not this time."

Monday, April 28, 2008

WASHINGTON (Reuters) — Before humans began burning fossil fuels, there was an eons-long balance between carbon dioxide emissions and Earth's ability to absorb them, but now the planet can't keep up, scientists said on Sunday.

The finding, reported in the journal, Nature Geoscience, relies on ancient Antarctic ice bubbles that contain air samples going back 610,000 years.

Climate scientists for the last 25 years or so have suggested that some kind of natural mechanism regulates our planet's temperature and the level of carbon dioxide in the atmosphere. Those skeptical about human influence on global warming point to this as the cause for recent climate change.

This research is likely the first observable evidence for this natural mechanism.

This mechanism, known as "feedback," has been thrown out of whack by a steep rise in carbon dioxide emissions from the burning of coal and petroleum for the last 200 years or so, said Richard Zeebe, a co-author of the report.

"These feedbacks operate so slowly that they will not help us in terms of climate change ... that we're going to see in the next several hundred years," Zeebe said by telephone from the University of Hawaii. "Right now we have put the system entirely out of equilibrium."

In the ancient past, excess carbon dioxide came mostly from volcanoes, which spewed very little of the chemical compared to what humans activities do now, but it still had to be addressed.

This antique excess carbon dioxide -- a powerful greenhouse gas -- was removed from the atmosphere through the weathering of mountains, which take in the chemical. In the end, it was washed downhill into oceans and buried in deep sea sediments, Zeebe said.

14,000 TIMES FASTER THAN NATURE

Zeebe analyzed carbon dioxide that had been captured in Antarctic ice, and by figuring out how much carbon dioxide was in the atmosphere at various points in time, he and his co-author determined that it waxed and waned along with the world's temperature.

"When the carbon dioxide was low, the temperature was low, and we had an ice age," he said. And while Earth's temperature fell during ice ages and rose during so-called interglacial periods between them, the planet's mean temperature has been going slowly down for about 600,000 years.

The average change in the amount of atmospheric carbon dioxide over the last 600,000 years has been just 22 parts per million by volume, Zeebe said, which means that 22 molecules of carbon dioxide were added to, or removed from, every million molecules of air.

Since the Industrial Revolution began in the 18th century, ushering in the widespread human use of fossil fuels, the amount of carbon dioxide in the atmosphere has risen by 100 parts per million.

That means human activities are putting carbon dioxide into the atmosphere about 14,000 times as fast as natural processes do, Zeebe said.

And it appears to be speeding up: the U.S. government reported last week that in 2007 alone, atmospheric carbon dioxide increased by 2.4 parts per million.

The natural mechanism will eventually absorb the excess carbon dioxide, Zeebe said, but not for hundreds of thousands of years.

"This is a time period that we can hardly imagine," he said. "They are way too slow to help us to restore the balance that we have now basically distorted in a very short period of time."

Saturday, April 26, 2008

BBC Online: Small changes to the way we live our lives are not enough to tackle the environmental challenges facing the planet, argues Tom Crompton. In this week's Green Room, he says the stark reality is that the only option is to cut the unsustainable consumption of the Earth's finite resources.

Having embraced one simple change, some people then tend to rest on their laurels

Almost daily, it seems, scientists' prognoses about the state of our planet grow evermore dire.

Take climate change, for example. Just last week, a new study suggested that sea levels could rise by up to one-and-a-half metres by the end of this century, with catastrophic impacts for low-lying countries.

This is more than three times as high as the most pessimistic projections of the Intergovernmental Panel on Climate Change (IPCC).

Yet some climatologists are suggesting that even this is a huge under-estimate of the likely extent of sea level rise.

In the face of mounting evidence of profound environmental challenges, the insistence that we can tackle these by embracing a few simple and painless changes - switching to low-energy light bulbs or buying a hybrid car - feels increasingly unrealistic.

'Simple and painless'

This is leading to heated debate among environmental organisations about the best response; a debate that WWF believes should be opened up to a wider audience.

Some measures make us feel better but do they make a difference?

Most approaches to encourage behavioural change rely on techniques borrowed from the marketing industry, such as "selling" these changes by linking them to a desirable product.

Those who practise these approaches often insist that, having made simple changes in their purchasing habitats, people will be led up a "virtuous ladder" towards ever more significant behavioural choices.

Marketing approaches may well work for promoting specific changes, where these are small and painless, and where they are the focus of a targeted campaign.

Unfortunately, as a response to problems of the scale that confront us, it seems that they are shot full of holes.

Of course, it's helpful for people to switch to energy-efficient light bulbs, or turn their central heating down; cumulatively, such changes will have a beneficial impact.

However, these sorts of campaigns may well be a poor use of scant communication resources, and may even serve to undermine prospects for generating the more fundamental changes that are needed.

There is little evidence to show that using such an approach increases the probability of people embarking upon more effective - and more difficult - changes.

In fact, some research shows that, for a significant number of people, the opposite is true. Having embraced one simple change, some people then tend to rest on their laurels and be less likely to engage in other more significant changes.

If I save money by repairing my old car rather than buying a new one, I could spend the savings on cheap flights abroad

But there's also another, more fundamental limitation on the usefulness of marketing approaches to creating behavioural change.

Environmental problems can often be traced to our appetite for "stuff", items that demand resources and energy in their manufacture, sale, use and disposal.

The problem is that we seem to have an in-built tendency not just to consume a lot of things, but to consume ever more things.

As a result, "green consumption" can only get us so far. I may buy this year's top-of-the-range hybrid car, only to want to replace it for a newer model next year, and the year after that.

It doesn't necessarily help if I'm encouraged that the best thing to do is to keep my car until it eventually falls apart.

If I save money by repairing my old car rather than buying a new one, I could spend the savings on cheap flights abroad. The net environmental impact will probably be negative.

Even selling my vehicle and joining a car-share scheme may backfire in this way, unless I am careful about how I spend the money that I've saved.

Less is more

As long as campaigns to encourage us to change our behaviour are based on appeals to self-interest or financial incentive, they will be fraught with difficulties.

Endless sales and bargains could be costing the Earth

We need a different approach to motivating people to change; one which stems from a re-examination of the values upon which this change is built.

Studies find that people who engage in behaviour in pursuit of "intrinsic" goals - such as personal growth, community involvement, or a sense of connection with nature - tend to be more highly motivated and more likely to engage in environmentally friendly behaviour than individuals who are motivated by "extrinsic" goals - that is, financial success, image and the acquisition of material goods.

This seems to be the case particularly for more difficult behaviours - those that require greater effort or entail more inconvenience.

There is a lot that governments can do to make environmentally friendly choices easier. But many of these things will cost taxpayers money, and governments will be reluctant to embark on these things without pressure from their electorates.

As in the case of individual behaviour change, if this pressure is to emerge, the values underlying this change in electoral demand will be critically important.

Bringing intrinsic values to the fore in public debate is not going to be easy. So we need to start trying to do so right away.

They should also work with leading businesses and forward-thinking political leaders to think beyond the opportunities offered by green consumerism; preparing for a world where we will inevitably need to consume not just differently, but less.

Environmental organisations can then help to embolden business and political leaders to begin to inject public debate with values that move far beyond self-interest and materialism.

To attempt less is increasingly looking like burying our heads in the sand.

More than 20 years of continuous measurements and a dose of "belief" yield discovery of subtle ocean currents that could dramatically improve forecasts of climate, ecosystem changes. An international collaboration of scientists led by Peter Niiler, a physical oceanographer at Scripps Institution of Oceanography, UC San Diego, and Nikolai Maximenko, a researcher at the International Pacific Research Center, University of Hawaii, has detected the presence of crisscrossing patterns of currents running throughout the world's oceans. The new data could help scientists significantly improve high-resolution models that help them understand trends in climate and marine ecosystems.A worldwide crisscrossing pattern of ocean current striations has been revealed through measurements made by drifting buoys over a period of more than 20 years and through satellite readings of ocean velocity. Blue bands represent westward-flowing currents and red bands indicate eastward-flowing currents that move at roughly 1 cm/s. (Credit: Image courtesy of Nikolai Maximenko, University of Hawaii.) Please click on image to enlarge it.

The basic dimensions of these steady patterns called striations have slowly been revealed over the course of several research papers by Niiler, Maximenko, and colleagues. An analysis by Maximenko, Niiler, and colleagues appearing today in the journal Geophysical Research Letters has produced the clearest representation of these striated patterns in the eastern Pacific Ocean to date and revealed that these complex patterns of currents extend from the surface to at least depths of 700 m (2,300 ft.). The discovery of similarly detailed patterns around the world is expected to emerge from future research.

Niiler credits the long-term and comprehensive ocean current measurements made over more than 20 years by the Global Drifter Program, now a network of more than 1,300 drifting buoys designed by him and administered by the National Oceanic and Atmospheric Administration (NOAA) for detecting these new current patterns on a global basis. Niiler added that the foresight of the University of California to provide long-term support to scientists was crucial to the discovery.

"I'm most grateful to the University of California for helping to support the invention and the 20-year maintenance of a comprehensive program of ocean circulation measurements," he said. "Scripps Institution of Oceanography is unique because of its commitment to long-term observations of the climate. Instrumental measurements of the ocean are fundamental to the definition of the state of the climate today and improvement of its prediction into the future."

In portions of the Southern Ocean, these striations-also known as ocean fronts-produce alternating eastward and westward accelerations of circulation and portions of them nearly circumnavigate Antarctica. These striations also delineate the ocean regions where uptake of carbon dioxide is greatest. In the Atlantic Ocean, these flows bear a strong association to the Azores Current along which water flowing south from the North Atlantic circulation is being subducted. The spatial high-resolution view of the linkage between the striations and the larger scale patterns of currents could improve predictions of ocean temperatures and hurricane paths.

In addition, the striations are connected to important ecosystems like the California and Peru-Chile current systems. Off California, the striations are linked to the steady east-west displacements, or meanders, of the California Current, a major flow that runs from the border of Washington and Oregon to the southern tip of Baja California. The striations run nearly perpendicular to the California Current and continue southwestward to the Hawaiian Islands.

Niiler said there are a number of scientists who have theorized the existence of striations in the ocean. He was the first to formulate such a theory as a postdoctoral researcher at Harvard University in 1965. Niiler's theory today is that the steady-state striations in the eastern North Pacific are caused by the angular momentum of the swirling eddies within the California Current System.

A worldwide crisscrossing pattern of ocean current striations has been revealed through measurements made by drifting buoys over a period of more than 20 years and through satellite readings of ocean velocity. Blue bands represent westward-flowing currents and red bands indicate eastward-flowing currents that move at roughly 1 cm/s. Image courtesy of Nikolai Maximenko, University of Hawaii.

The new maps of ocean circulation produced by a combination of drifter and satellite measurements will eventually be the yardstick for judging the accuracy of the circulation patterns portrayed by climate and ocean ecosystem models -- a major deficiency in current simulations -- and to generate substantially more reliable forecast products in climate and ecosystem management. Niiler noted, for example, that there are a large number of computer models that can simulate equatorial currents, but fail in the attempt to accurately simulate the meandering flow of the California Current and the striations that exude from it.

"I think this research presents the next challenge in ocean modeling," said Niiler. "I'm looking forward to the day when we can correctly portray most ocean circulation systems with all climate and ecosystem models."

Maximenko said the clear resolution of the subtle striations would not have been possible without the use of data from both the drifters and satellites.

"Our finding was so unbelievable that our first proposal submitted to the National Science Foundation failed miserably because most reviewers said 'You cannot study what does not exist,'" Maximenko said. "The striations are like ghosts. To see them one needs to believe in them. No doubt, armed with our hint, scientists will start finding all kinds of striations all around the world."

Maximenko, Niiler, and their international colleagues are now writing a series of papers that reveal new details about the crisscross patterns and their ties to currents such as the Kuroshio, which flows in western Pacific Ocean waters near Japan.

NOAA, the National Science Foundation, the NASA Ocean Surface Topography Team, and the Japan Agency for Marine-Earth Science and Technology supported the research.

University of California - San Diego (2008, April 26). Scientists Reveal Presence of Ocean Current 'Stripes'. ScienceDaily. Retrieved April 26, 2008, from http://www.sciencedaily.com­/releases/2008/04/080425095207.htm

Ecological Applications

Volume 18, Issue sp2 (March 2008)

published by the Ecological Society of America

While the Earth’s climate has exhibited broad extremes over geologic time, there is general agreement that the effects of global warming ongoing now are accentuated in the Arctic, and that the rate of environmental change may be unprecedented. How marine mammals respond to environmental change depends on a species’ adaptability, given its natural history and the temporal and spatial scale of perturbation. Although loss of sea ice as a platform for polar bears to hunt and walrus to rest grabs news headlines, there has been no rigorous effort to investigate either climate change or environmental responses, including those by humans, at the ecological scale of Arctic marine mammals. Here, we attempt just such an investigation through a collection of papers drafted by specialists in a cross-section of disciplines.

Why this collection of papers?—As Arctic sea ice is diminished, ice-associated marine mammals will be affected directly and indirectly. The overall area of sea ice habitat will shrink, reducing the range of ice-obligate species (e.g., ringed seal and polar bear). Ice substrate for breeding and resting will be lost, as will seasonal proximity between ice and key bathymetric features such as shallow continental shelves. Ecological process of the Arctic will change in many ways, while human activities such as shipping and resource development in the region will likely increase. The relationship among marine mammals, indigenous hunters, commercial interests, and sea ice will be sharply altered.

Such conclusions may seem self-evident, but understanding the specific mechanisms by which climate change will affect Arctic marine mammals is important both for its own sake and for determining the extent to which conservation strategies can help prevent or mitigate any negative impacts. A thorough assessment of this topic, involving several perspectives and disciplines, will help identify the species, characteristics, and regions of greatest vulnerability.

Four papers set the stage for assessing current and future status of Arctic marine mammals with respect to climate change. Walsh reviews current climatological understanding, including model projections for the coming century. Harington describes the evolutionary history of Arctic marine mammals. Murray discusses what zooarchaeology teaches us about past distributions. O’Corry-Crowe uses molecular genetics to investigate past and current distributions and behaviors.

The next four papers cover the potential effects of climate change on various aspects of Arctic marine mammals’ natural history and ecology. Bluhm and Gradinger discuss productivity and prey. Laidre et al. consider habitats. Burek et al. describe body condition and health. Hovelsrud et al. review human interactions. Metcalf and Robards examine the case of walrus hunting in western Alaska.

Finally, two papers synthesize the findings of the preceding papers to assess overall impacts and resilience of marine mammals (Moore & Huntington) and the potential for conservation action (Ragen et al.). Taken together, the papers provide a multidisciplinary, authoritative summary of current knowledge to serve both as a baseline for future assessments and as the basis for action in research and in conservation.

Defining the Arctic and Arctic marine mammals.—Simple and satisfactory definitions of the Arctic are elusive. Astronomical, climatological, oceanographic, botanic, and other boundaries have their strengths and weaknesses. For our purposes, we consider the Arctic marine environment to be the region where sea ice is a dominant feature for a considerable part of the year. Our region therefore includes the Arctic Ocean proper as well as the Barents and Bering seas and Hudson and Baffin bays. The Sea of Okhotsk and the Norwegian, Greenlandic, and Icelandic seas share some characteristics and species with the Arctic but are not included in the core Arctic region for our purposes.

More pertinent than a geographical limit, however, is the question of which species should beconsidered ‘‘Arctic’’ for our assessment. Many species visit the Arctic at various times or are found in proximity to sea ice at some point in their migrations or life cycle. Relatively few species actually require sea ice for their survival, though it appears to be preferred habitat for several. Some species are found year-round in the Arctic but also have separate stocks in more southerly locations. While any species list has an element of arbitrariness, we have chosen as ‘‘core species’’ for this assessment the seven that occupy the Arctic environment and for which at least some portion of the population is associated with sea ice year-round:

These species are considered in all papers, and a summary of habitat and range for each appears in Laidre et al. in this volume.

In addition, nine other species are seasonal or occasional migrants to the Arctic or have someassociation with sea ice. These include the harp seal (Phoca groenlandica), hooded seal (Cystophora cristata), ribbon seal (Phoca fasciata), spotted seal (Phoca largha), gray whale (Eschrichtius robustus), killer whale (Orcinus orca), minke whale (Balaenoptera acutorostrata), fin whale (Balaenoptera physalus), and humpback whale (Megaptera novaeangliae). Discussion of these species has been included where they either shed light on the core species or where changes in the core Arctic region are expected to have a significant effect on any one of these species. The reader is directed to species accounts in natural history guides for additional background information.

Acknowledgments.—We thank the Marine Mammal Commission (USA) for supporting thepreparation and publication of this Special Issue. We also thank the reviewers of the papers in this collection for their encouragement and constructive criticism.

You know when climate change is biting hard when instead of a vast expanse of snow the North Pole is a vast expanse of water. This year, for the first time, Arctic scientists are preparing for that possibility.

"The set-up for this summer is disturbing," says Mark Serreze, of the US National Snow and Ice Data Center (NSIDC). A number of factors have this year led to most of the Arctic ice being thin and vulnerable as it enters its summer melting season.

The ice expanded again over the winter and in March 2008 covered a greater area than it had in March 2007. Although this was billed as good news in many media sources, the trend since 1978 is on the decline.

Young and thin

Arctic ice at its maximum in March, but that maximum is declining by 44,000 km2 per year on average, the NSIDC has calculated. That corresponds to an area roughly twice the size of New Jersey.

Thin ice is far more vulnerable than thick ice that has piled up over several years.

Net loss

"There is this thin first-year ice even at the North Pole at the moment," says Serreze. "This raises the spectre – the possibility that you could become ice free at the North Pole this year."

Despite its news value in the media, the North Pole being ice free is not in itself significant. To scientists, Serreze points out, "this is just another point on the globe." What is worrying, though, is the fact that multi-year ice – the stuff that doesn't melt in the summer – is not piling up as fast as Arctic ice generally is melting.

On average each year about half of the first year ice, formed between September and March, melts during the following summer. In 2007, nearly all of it disappeared.

Moreover, an atmospheric phenomenon known as the Arctic oscillation kicked into its strong, "positive," phase this winter. This is known to generate winds which push multi-year ice out of the Arctic along the east coast of Greenland.

Ice still possible

Together, these are the factors that have led to most of the Arctic ice now being so young and thin.

"Even if you lost only half of the first-year ice this year – which would be average – you are still in for a very low ice extent this summer," says Serreze.

Some factors could still save the day, though. In summer 2007, warm winds favoured melting. "If we have an atmospheric pattern like we had last year, we are going to lose a whole bunch of ice this summer, but if we have a cooler, more cyclonic pattern, that might preserve some of that ice," says Serreze.

BLOGGER'S NOTE: A commenter on the realclimate blog has recently left links to 3 abstracts of interest and concerning changes in the temperatures, locations, and winds of the troposphere and stratosphere.__________________________________________________________________

The atmosphere's lowermost 10 km have long been assumed to be almost solely responsible for weather and climate on Earth. Emerging evidence points to the layer above as an important influence on surface winds and temperatures on seasonal to decadal timescales.

The spatial distribution of tropospheric and stratospheric temperaturetrends for 1979 to 2005 was examined, based on radiances fromsatellite-borne microwave sounding units that were processedwith state-of-the-art retrieval algorithms. We found that relativeto the global-mean trends of the respective layers, both hemisphereshave experienced enhanced tropospheric warming and stratosphericcooling in the 15° to 45° latitude belt, which is a patternindicative of a widening of the tropical circulation and a polewardshift of the tropospheric jet streams and their associated subtropicaldry zones. This distinctive spatial pattern in the trends appearsto be a robust feature of this 27-year record.

Abstract

Some of the earliest unequivocal signs of climate change have been the warming of the air and ocean, thawing of land and melting of ice in the Arctic. But recent studies are showing that the tropics are also changing. Several lines of evidence show that over the past few decades the tropical belt has expanded. This expansion has potentially important implications for subtropical societies and may lead to profound changes in the global climate system. Most importantly, poleward movement of large-scale atmospheric circulation systems, such as jet streams and storm tracks, could result in shifts in precipitation patterns affecting natural ecosystems, agriculture, and water resources. The implications of the expansion for stratospheric circulation and the distribution of ozone in the atmosphere are as yet poorly understood. The observed recent rate of expansion is greater than climate model projections of expansion over the twenty-first century, which suggests that there is still much to be learned about this aspect of global climate change.

NOAA Air Resources Laboratory, Silver Spring, MD, USA

University of Washington, Department of Atmospheric Sciences, Seattle, WA, USA

Abstract

Jet streams, the meandering bands of fast winds located near the tropopause, are driving factors for weather in the midlatitudes. This is the first study to analyze historical trends of jet stream properties based on the ERA-40 and the NCEP/NCAR reanalysis datasets for the period 1979 to 2001. We defined jet stream properties based on mass and mass-flux weighted averages. We found that, in general, the jet streams have risen in altitude and moved poleward in both hemispheres. In the northern hemisphere, the jet stream weakened. In the southern hemisphere, the sub-tropical jet weakened, whereas the polar jet strengthened. Exceptions to this general behavior were found locally and seasonally. Further observations and analysis are needed to confidently attribute the causes of these changes to anthropogenic climate change, natural variability, or some combination of the two.

Received 12 February 2008; accepted 14 March 2008; published 18 April 2008.

Friday, April 25, 2008

Scientists in the U.S. have presented one of the most dramatic forecasts yet for the disappearance of Arctic sea ice.

Their latest modelling studies indicate northern polar waters could be ice-free in summers within just 5-6 years.

Professor Wieslaw Maslowski told an American Geophysical Union meeting that previous projections had underestimated the processes now driving ice loss.

Summer melting this year reduced the ice cover to 4.13 million sq km, the smallest ever extent in modern times.

Remarkably, this stunning low point was not even incorporated into the model runs of Professor Maslowski and his team, which used data sets from 1979 to 2004 to constrain their future projections.

In the end, it will just melt away quite suddenly

Professor Peter Wadhams

"Our projection of 2013 for the removal of ice in summer is not accounting for the last two minima, in 2005 and 2007," the researcher from the Naval Postgraduate School, Monterey, California, explained to the BBC.

"So given that fact, you can argue that may be our projection of 2013 is already too conservative."

Real world

Using supercomputers to crunch through possible future outcomes has become a standard part of climate science in recent years.

Professor Maslowski's group, which includes co-workers at NASA and the Institute of Oceanology, Polish Academy of Sciences (PAS), is well known for producing modelled dates that are in advance of other teams.

These other teams have variously produced dates for an open summer ocean that, broadly speaking, go out from about 2040 to 2100.

But the Monterey researcher believes these models have seriously underestimated some key melting processes. In particular, Professor Maslowski is adamant that models need to incorporate more realistic representations of the way warm water is moving into the Arctic basin from the Pacific and Atlantic oceans.

"My claim is that the global climate models underestimate the amount of heat delivered to the sea ice by oceanic advection," Professor Maslowski said.

"The reason is that their low spatial resolution actually limits them from seeing important detailed factors.

"We use a high-resolution regional model for the Arctic Ocean and sea ice forced with realistic atmospheric data. This way, we get much more realistic forcing, from above by the atmosphere and from the bottom by the ocean."

The Intergovernmental Panel on Climate Change (IPCC), the UN-led body which assesses the state of the Earth's climate system, uses an averaged group of models to forecast ice loss in the Arctic.

But it is has become apparent in recent years that the real, observed rate of summer ice melting is now starting to run well ahead of the models.

The minimum ice extent reached in September 2007 shattered the previous record for ice withdrawal set in 2005, of 5.32 million sq km.

The long-term average minimum, based on data from 1979 to 2000, is 6.74 million sq km. In comparison, 2007 was lower by 2.61 million sq km, an area approximately equal to the size of Alaska and Texas combined, or the size of 10 United Kingdoms.

Diminishing returns

Professor Peter Wadhams from Cambridge University, UK, is an expert on Arctic ice. He has used sonar data collected by Royal Navy submarines to show that the volume loss is outstripping even area withdrawal, which is in agreement with the model result of Professor Maslowski.

"Some models have not been taking proper account of the physical processes that go on," he commented.

"The ice is thinning faster than it is shrinking; and some modellers have been assuming the ice was a rather thick slab.

"Wieslaw's model is more efficient because it works with data and it takes account of processes that happen internally in the ice."

He cited the ice-albedo feedback effect in which open water receives more solar radiation, which in turn leads to additional warming and further melting.

Professor Wadhams said the Arctic was now being set up for further ice loss in the coming years.

"The implication is that this is not a cycle, not just a fluctuation. The loss this year will precondition the ice for the same thing to happen again next year, only worse.

"There will be even more opening up, even more absorption and even more melting.

"In the end, it will just melt away quite suddenly. It might not be as early as 2013, but it will be soon, much earlier than 2040."

The U.S. National Snow and Ice Data Center (NSIDC) collects the observational data on the extent of Arctic sea ice, delivering regular status bulletins. Its research scientist Dr Mark Serreze was asked to give one of the main lectures here at this year's AGU Fall Meeting.

Discussing the possibility for an open Arctic ocean in summer months, he told the meeting: "A few years ago, even I was thinking 2050, 2070, out beyond the year 2100, because that's what our models were telling us. But as we've seen, the models aren't fast enough right now; we are losing ice at a much more rapid rate.

"My thinking on this is that 2030 is not an unreasonable date to be thinking of."

And later, to the BBC, Dr Serreze added, "I think Wieslaw is probably a little aggressive in his projections, simply because the luck of the draw means natural variability can kick in to give you a few years in which the ice loss is a little less than you've had in previous years. But Wieslaw is a smart guy and it would not surprise me if his projections came out."

Former U.S. Vice President Al Gore cited Professor Maslowski's analysis on Monday in his acceptance speech at the Nobel Peace Prize ceremony in Oslo.

Thursday, April 24, 2008

International efforts are gaining momentum to hammer out a new climate change agreement to replace the Kyoto Protocol when it expires in 2012.

A new plan from U.S. President George Bush which aims to cap greenhouse gases by 2025 has been dismissed as "disastrous" and "Neanderthal" by a group of ministers at a climate change meeting in Paris.

This week Mr Bush said he wanted to stop the growth of U.S. emissions by 2025, taking a stronger stance on the issue than in the past.

However his plan, announced at a ministerial-level meeting of major carbon emitters, has drawn criticism from delegates from Australia, the European Union and some U.S. participants.

Germany says Mr Bush has taken climate change policy back in time, to before last December's UN climate talks in Bali and last July's G8 summit.

In a statement called "Bush's Neanderthal speech," German Environment Minister Sigmar Gabriel said: "His speech showed not leadership but losership. We are glad that there are also other voices in the United States."

South Africa said Mr Bush's proposal was a disastrous effort from the world's biggest carbon polluter and a "slap" to developing countries.

International efforts are gaining momentum to hammer out a successor agreement to the Kyoto Protocol when it expires in 2012.

The talks in Bali produced a two-year "roadmap" intended to lead towards a global agreement on carbon emissions by 2013.

Climate experts say any new agreement must form a bridge between the U.S. and the EU, on the one hand, and developing nations on the other.

Mr Bush's critics say that instead of setting a date for cutting U.S. emissions, he had merely chosen the year 2025 for them to peak.

He also renewed his attack on Kyoto-style mandatory emissions caps, and pressed big emerging countries to make concessions, saying they should not get "a free ride" in the next climate treaty.

Wednesday, April 23, 2008

Although the world's oceans are expected to warm up as a result of climate change, the way this happens will be more complex than first thought. So say researchers in the US and UK who have found that, while the North Atlantic Ocean has become warmer over the last 50 years, this change has not been uniform. Instead, the subpolar regions have cooled and tropical regions warmed, so masking the overall effects of anthropogenic warming.

Susan Lozier at Duke University, US, and Richard Williams at Liverpool University, UK, and co-workers analysed temperature data from the National Oceanic Data Center World Ocean Database from 1950 to 2000. They interpreted the data by using circulation model experiments driven by realistic surface air-sea fluxes and winds over this period. The model predicts how winds, evaporation, rainfall and heat exchange with the atmosphere affect the North Atlantic Ocean's heat content over time.

The experiments showed that water in the subpolar North Atlantic Ocean (north of 45° latitude) became cooler as it exchanged heat with the air above it. In contrast, the subtropical and tropical ocean (south of 45° latitude) warmed up.

"The experiments revealed that much of the heat changes over the North Atlantic Ocean were associated with a wind-induced redistribution of heat together with a background input of heat in the tropics," Williams told environmentalresearchweb. This pattern can be explained by the large-scale change in the wind pattern – as measured by the North Atlantic Oscillation (NAO) index defined by differences in sea-level pressures. This atmospheric variability changes from year-to-year and over decades.

"Heat changes in the ocean show a much more complicated response than expected over the North Atlantic," explained Williams. "The variability in ocean heat content appears to be associated with changes in atmospheric wind forcing, which varies on a decadal timescale. At the moment, it is unclear as to which parts of this warming signal induced by the wind forcing link back to anthropogenic forcing and which parts reflect natural changes in the climate."

The researchers went on to say that they do not want their work to be used as part of a referendum as to whether greenhouse warming is happening. "Anthropogenic warming is almost certainly occurring given the wide range of global signals, including rise in surface and atmospheric temperatures, rise in sea levels, and decline in summer sea ice in the Arctic," stressed Williams. However, these "background" trends could also be being masked by changes that occur over decades on regional scales, he added.

"In our study, we have shown that regional signals in the North Atlantic have a more complex pattern than initially expected, where decadal variability might be masking any background warming trend," he said.

The team will now extend the ocean data analysis and model investigations to further examine interior ocean temperature changes.

On 28th and 29th February 2008, a 400 sq. km area of the Wilkins Ice Shelf on the Antarctic Peninsula broke up. That adds to the total of seven ice shelves that have disappeared in the West Antarctic between 1995 and 2002, a phenomenon believed to be due to increased temperatures.

According to Angelika Humbert of Darmstadt University of Technology and Matthias Braun of Bonn University, both in Germany, the area of loss in February is less spectacular than the effect on the whole ice shelf. The fracture created a large number of intersecting rifts in around 5000 sq. km of the northern part of the ice shelf.

"The failure zones from the break-up make the shelf vulnerable," said Braun.

Over the past two years, Humbert and Braun have examined 22 years' worth of European Space Agency remote sensing data for the region. They believe their study of the break-up has given them new insights into some of the mechanisms behind ice shelf failures.

Rifts and failure zones first started to develop on the Wilkins Ice Shelf in 1993/94, according to the researchers. In February 2008 a rift formed very quickly between the central part of Wilkins Ice shelf and the stabilizing Charcot Island -- on a scale of just minutes. The connection lost 40% of its total size.

The pair have mapped visible structures on the ice shelf, such as flow lines, rifts and grounded areas. They say that the Wilkins shelf is unusual in having lots of small ice rises -- areas that protrude above the surface where the ice shelf meets the seabed below. The rises, which on Wilkins generally have a diameter less than 1 km, divide the ice flow and cause small rifts, acting as nuclei for the development of failure zones. During the February breakup, these rifts typically extended to roughly 20 km either side of the rises. A number of new rifts also formed.

"The rift zones are connected now and that makes a part of the ice shelf vulnerable to breakup," said the researchers. This is the first time they have seen such a creation of new ice rifts and joining of existing rifts -- they believe it may be unique. The result is a more fragile ice shelf.

Humbert and Braun reckon that unequal buoyancy forces arising from differences in ice thickness may have caused the accumulation of bending stress, leading to this rift behavior. They are currently looking at further observations to find out more and say that more satellite measurements and field surveys of ice shelves are needed to help examine the causes of ice shelf disintegration.

The Wilkins Ice shelf is confined by four islands -- Alexander, Latady, Charcot, and Rothschild, giving it a fairly unique structure. The northeastern part of the ice shelf is around 50-150 m thick while the western and southern regions are thicker, with ice 170-270 m thick.

The shelf is unusual in that it receives only a small contribution from glaciers, gaining most of its mass from snow build up. Wilkins loses most of its mass by basal melting, as well as experiencing discontinuous fast breakup events rather than the slower, more standard iceberg calving that occurs elsewhere. The shelf is also comparably warm, with a temperature of -9 °C at the surface.

Humbert and Braun reported their work at the European Geosciences Union General Assembly in Vienna, Austria. They have submitted papers to Geophysical Research Letters and to The Cryosphere.

WASHINGTON -- Major greenhouse gases in the air are accumulating faster than in the past despite efforts to curtail their growth.

Carbon dioxide concentration in the air increased by 2.4 parts per million last year, the National Oceanic and Atmospheric Administration reported Wednesday, and methane concentrations also rose rapidly.Global averages of the concentrations of the major, well-mixed, long-lived greenhouse gases (carbon dioxide, methane, nitrous oxide, CFC-12 and CFC-11) from the NOAA global flask sampling network since 1978. These gases account for about 97% of the direct radiative forcing by long-lived greenhouse gases since 1750. The remaining 3% is contributed by an assortment of 10 minor halogen gases. Methane data prior to 1983 are annual averages from Etheridge et al. (1998), adjusted to the NOAA calibration scale [Dlugokencky et al., 2005]. Click on image to view full size figure.

Concern has grown in recent years about these gases, with most atmospheric scientists concerned that the increasing accumulation is causing the earth's temperature to rise, potentially disrupting climate and changing patterns of rainfall, drought and other storms.

The Intergovernmental Panel on Climate Change has worked to detail the scientific bases of this problem and the Kyoto agreement sought to encourage countries to take steps to reduce their greenhouse emissions. Some countries, particularly in Europe, have taken steps to reduce emissions.

But carbon dioxide emissions, primarily from burning fossil fuels such as coal, oil and gas have continued to increase.

Since 2000, annual increases of two parts per million or more have been common, compared with 1.5 ppm per year in the 1980s and less than one ppm per year during the 1960s, NOAA's Earth System Research Laboratory said.

Global concentration of carbon dioxide is now nearly 385 parts per million. Preindustrial carbon dioxide levels hovered around 280 ppm until 1850. Human activities pushed those levels up to 380 ppm by early 2006.

Rapidly growing industrialization in Asia and rising wetland emissions in the Arctic and tropics are the most likely causes of the recent methane increase, said Ed Dlugokencky from NOAA's Earth System Research Laboratory.

Methane in the atmosphere rose by 27 million tons last year after nearly a decade with little or no increase, he said.

Methane is 25 times more potent as a greenhouse gas than carbon dioxide, but there's far less of it in the atmosphere. When related climate affects are taken into account, methane's overall climate impact is nearly half that of carbon dioxide.___On the Net:Earth System Research Laboratory: http://www.esrl.noaa.gov/gmd/aggi

Monday, April 21, 2008

Hank Roberts was kind enough to post the explanation (although, looking at this evening's graph, I must admit, after viewing the 4 graphs, that I still have no idea what is going on with them -- only time will tell, it seems):

"The satellite data sources for these products, while generally providing complete coverage, are subject to gaps (shown in dark grey) in coverage because of satellite operations. In the daily extent time series, gaps are replaced with values interpolated from surrounding days, but temporary spurious results may occur. The current satellite source is aging and showing more frequent data gaps. NSIDC is investigating a reliable replacement data source. —Credit: National Snow and Ice Data Center"Blogger's note -- update of April 23 (morning): This just gets weirder and weirder. April 20 shows one thing, April 21 another, and now April 23 looks more like April 20 again. Anyway, I guess the NSIDC are the only ones who can tell us how they update this graph.

ABOVE: Graph from April 20, 2008.

BELOW: Graph from April 21, 2008.

BELOW: Graph from the morning of April 23rd, 2008.(Once again, thank you to Leon for pointing it out to me.)

Sunday, April 20, 2008

FOR all its Old West mythology, Wyoming is and always will be a mining state, more roughneck than cowboy. Frankly, in a land of long winters and high winds, there aren’t a lot of other economic choices. And a powerful oil lobby reminds us with Orwellian regularity that we owe everything to oil and gas taxes, bullying those who disagree. (In February, a committee of the Wyoming Legislature rejected a spending increase for the University of Wyoming’s Ruckelshaus Institute of Environment and Natural Resources after institute scientists dared to raise concerns about water produced in coal-bed methane wells.) Even so, the oilier side of our nature has never threatened to unhorse the cowboy entirely, not even now, when the pressure to develop every last seam of energy is end-of-administration intense.

Since 1996, oil and gas companies have leased from the federal government the mineral rights to nearly 27 million acres of land in the Rocky Mountain West, and Wyoming has shouldered the greatest share of that development. In the last decade, oil companies have leased a fifth to a quarter of the state’s land — 15.5 million acres administered by the Bureau of Land Management, as well of hundreds of thousands of acres of national forest and private land. If Wyoming were a country, it would be one of the largest coal-producing nations in the world, and its output of natural gas is among the greatest in American history. The argument has never been that we shouldn’t provide energy. But is that all we’re good for? And what, if anything, should we leave for future generations? These are global questions posed on a local level.

During his second term, President Bill Clinton, under pressure from a Republican Congress, leased out just as much of Wyoming’s land as the current administration has to date. The difference was that the Clinton administration enforced laws encouraging the Bureau of Land Management to “manage, protect and improve” our public lands while allowing for other values like recreation, grazing and wildlife habitat. The Bush administration, on the other hand, has lifted every possible impediment to industry.

For example, oil and gas companies are exempt from provisions of the Clean Water Act that require construction activities to reduce polluted runoff as well as from provisions of the Safe Drinking Water Act that regulate underground injection of chemicals. The industry is also generously permitted to drill on critical wildlife winter range (close to 90 percent of all their requests to drill on winter range have been granted). Oil rigs are drilling for natural gas on the banks of the New Fork River (the headwaters of the Colorado) and in the foothills of the Wyoming Range. Well sites in many parts of the southern Greater Yellowstone Ecosystem are so closely spaced that, with roads, gas pipelines and compressor stations, the development is continuous.

Meantime, drug treatment centers and domestic abuse shelters across the state have declared themselves overwhelmed and, in spite of what the oil companies keep telling us, we’re far from happy. Wyoming has the uneasy distinction of having one of the country’s highest suicide rates. We top the national death toll on the job with 16.8 deaths per 100,000 workers. Wyoming is responsible for by far the highest percentage of deaths on the job in the interior West’s oil and gas industry. At public meetings organized by the Bureau of Land Management to announce the development of Wyoming’s public lands, oil company executives initially argued to a largely receptive audience that a new boom would be good for the state’s economy. Lately, executives have been telling increasingly unhappy communities that domestic drilling is our moral duty, an alternative to sending more soldiers to war. They imply that anything less than full support for the oil companies is un-American. But a bumper sticker on a pick-up truck hints at the truth: “The war is over. Halliburton won.”

Meanwhile, cattle and sheep ranchers and hunting and tourist guides have found themselves wondering what has happened to their Wyoming. Wildlife suffers as oil leases overlap with habitat: 14.1 million acres of sage grouse habitat, 3.2 million acres of pronghorn winter habitat, 2.9 million acres of mule deer winter habitat and 1.1 million acres of elk winter habitat. Even most of the state’s wild horse herd management areas (the only Wyoming lands on which wild horses may legally roam) are destined for oil development.

Eighty-five water wells in the southern Greater Yellowstone Ecosystem have recently tested positive for hydrocarbons, indicating that toxic chemicals from drilling have leaked into the water table. Air pollution in the same area was so great this winter that vulnerable residents were warned not to venture outside. Oil companies argued that strong winds would rectify the problem.

They were right to predict a wind of change, but it came in the form of an unprecedented experiment in the art of listening. In the last few months, Terry Tempest Williams, a writer in residence at the University of Wyoming, has taken her students on the road to conduct what she calls “weather reports” in small communities. Addressing packed rooms, Ms. Williams turns the microphone over to the people of Wyoming — a stoical populace whose habitual stance against something they don’t like is a tight lip. Astonishingly, they have opened up, voicing their concerns over the rapidity and scale of the oil and gas development.

“One day, I fear I will wake up and all that will be left of Wyoming is a hole in the ground,” one resident of the southern Greater Yellowstone Ecosystem said.

Oil executives have pushed back. One oilman, State Senator Kit Jennings, took the microphone in Casper and declared that Ms. Williams had demonized the oil companies. He rejected her contention in a local newspaper article that the energy boom had helped drive up the use of crystal methamphetamine in the region and announced that he had demanded that she be fired from the university for her criticism of the industry.

Oil and gas are accustomed to dominating the debate. But Ms. Williams’s forums have created an opportunity for grass-roots rebuttal. Residents, who have so far been cowed by the enormous tax contributions that energy companies make to the state’s coffers, are upholding values not counted in dollars. “My hope is that with our backs against the wall we will finally speak up,” another weather reports participant said.

Maybe Wyomingites, justifiably proud of their roughneck heritage and anxious to keep the oil field work, have realized that this boom isn’t going away soon, and they’d like a little of Wyoming left when the oil companies move back to Texas. “We’re Mother Nature’s bodyguards,” a billboard sponsored by Sportsmen for the Wyoming Range warns. “And yes, we are heavily armed.”

The jet stream -- America's stormy weather maker -- is creeping northward and weakening, new research shows. That potentially means less rain in the already dry South and Southwest and more storms in the North.

And it could also translate into more and stronger hurricanes, since the jet stream suppresses their formation. The study's authors said they have to do more research to pinpoint specific consequences.

From 1979 to 2001, the Northern Hemisphere's jet stream moved northward on average at a rate of about 1.25 miles a year, according to the paper published Friday in the journal Geophysical Research Letters. The authors suspect global warming is the cause, but have yet to prove it.

The jet stream is a high-speed, constantly shifting river of air about 30,000 feet above the ground that guides storm systems and cool air around the globe. And when it moves away from a region, high pressure and clear skies predominate.

Two other jet streams in the Southern Hemisphere are also shifting poleward, the study found.

The northern jet stream "is the dominant thing that creates weather systems for the United States," said study co-author Ken Caldeira, a climate scientist at the Carnegie Institution of Washington in Stanford, Calif. "Bascially look south of where you are and that's probably a good guess of what your weather may be like in a few decades."

The study looked at the average location of the constantly moving jet stream and found that when looked at over decades, it has shifted northward. The study's authors and other scientists suggest that the widening of the Earth's tropical belt -- a development documented last year -- is pushing the three jet streams toward the poles.

Climate models have long predicted that with global warming, the world's jet streams would move that way, so it makes sense to think that's what happening, Caldeira said. However, proving it is a rigorous process, using complex computer models to factor in all sorts of possibilities. That has not been done yet.

A rate of 1.25 miles a year "doesn't sound like much, but that works out to about 18 feet per day," Caldeira said. "If you think about climate zones shifting northward at this rate, you can imagine squirrels keeping up. But what are oak trees going to do?

"We are seeing a general northward shift of all sorts of phenomena in the Northern Hemisphere occurring at rates that are faster than what ecosystems can keep up with," he said.

Dian Seidel, a research meteorologist for the National Oceanic and Atmospheric Administration who wrote a study about the widening tropical belt last year, said she was surprised that Caldeira found such a small shift. Her study documented that the tropical belt was bulging at a much faster rate. Caldeira said his figures represent the minimum amount of movement.

The jet stream also factors into bumpy air travel. It is a cause of clear air turbulence that airline pilots try to avoid by tracking where the jet stream is.

Is the Arctic's biggest ice sheet in irreversible meltdown? And would we know if it were? Alexandra Witze reports.

I. JOUGHIN

When people talk about catastrophic climate change, there's a fair chance that Greenland is on their mind. If they use the term 'tipping point', then it is pretty much a sure thing. One-twentieth of the world's ice is locked up atop that island, and if it were to melt completely, global sea levels would rise by seven metres. The collapse of the Greenland ice sheet is in the front rank of potential climate catastrophes.

Melting is already undoubtedly and dramatically underway. Glaciers are spitting icebergs into the ocean and scurrying back up their narrow fjords like rats up drainpipes. Giant lakes are forming on the frozen surface, sending torrents of water plunging through fissures in the ice sheet and thus, perhaps, accelerating its slipping and sliding seawards. Over the past four summers, Greenland has shed an average of between 380 billion tonnes and 490 billion tonnes of ice each year — on average 150 billion tonnes more than it gains in snow in winter.

That's a lot of water. It is not, as yet, a lot of Greenland's ice, which totals 2.9 million cubic kilometres. Such size brings with it an inherent sense of stability. We do not expect things bigger than mountain ranges just to go away. But there's a disturbing sense in which Greenland shouldn't be here in the first place. It is a holdover of the most recent ice age, a creature of conditions that no longer apply. No ice sheet would grow in Greenland if the current one were to vanish — even without human-induced warming, the climate would not allow it. The ice is a relic, stranded out of time. And relics are fragile.

The question is, how fragile? Has the warming the sheet has experienced so far and the further warming already in the pipeline enough to push the ice sheet past a point of no return1? If that is not yet the case, how far from that threshold are we? And if the sheet does start to go, how fast will it do so? The sheet will not vanish tomorrow, nor in a century — but assumptions that such processes take millennia are being reexamined on the basis of the changes already seen. The most recent synthesis report from the Intergovernmental Panel on Climate Change notes that the changes seen in Greenland today are not fully factored into the estimates of sea-level rise given in earlier science reports from the panel — a note that those who see Greenland as a potential poster child for catastrophe have made much of.

As yet, these pressing questions simply cannot be answered. They require models and theories not yet fully developed. And that lack of development is in part a lack of data — good data that show clear trends. Even though researchers scatter themselves around the island every summer to try to capture the meltdown's extent and processes, there is no systematic, long-term, broadly based monitoring of the sort needed to produce a truly comprehensive account of what is happening with the ice sheet. “Do we have the data we need to understand what's driving these changes?” asks Ian Howat, a glaciologist at Ohio State University in Columbus. “The answer is definitely no.”

The gravity of the situation

To get the best overview of the great Greenland meltdown, you need to go to space and look for gravity. The Gravity Recovery and Climate Experiment (GRACE) is a pair of US–German satellites that orbit Earth 500 kilometres up, one close behind the other. Through constant interchange of microwaves the satellites measure the distance between them very precisely, and that distance changes as massive objects below tug at the leader and the follower in slightly different ways at any given instant. The small discrepancies so produced can be used to calculate a gravity map for the planet. As masses move around, that map will change.

“2007 was a shocking year.” Scott Luthcke

Data from GRACE have revealed how the water flow in the Amazon basin changes with the seasons, and which Asian aquifers are replenished by the monsoons. The mission has also provided new information about the flow of water off the massive ice sheets in Greenland and Antarctica. “When you look at a lot of the insight we have” about Greenland, says Konrad Steffen, a glaciologist at the University of Colorado at Boulder, “it's GRACE.”

The estimates vary as to how much mass is lost through melting each summer. Isabella Velicogna of the University of California, Irvine, leads a group that takes a large-scale approach2, averaging the global gravity numbers provided by GRACE for each 30-day period. Her latest estimate suggests that 211 billion tonnes of ice are being lost each year, mainly from southern Greenland. “There is no doubt that things are changing faster than we expected,” she says. Meanwhile, Scott Luthcke of NASA's Goddard Space Flight Center in Greenbelt, Maryland, takes a different tack, using the changing distance between the satellites to calculate the pull of smaller mass concentrations on the ground over time3. Including the 2007 melt season, he gets preliminary estimates of 154 billion tonnes of ice lost per year. The numbers sound different, but both groups emphasize how close they are, and over time there seems to be some convergence. “These are two vastly different ways of processing data, and they're almost within the error bars,” says Luthcke. “Greenland is losing a lot of mass.”

GRACE is also providing clues as to how the situation varies from year to year — particularly for the last melt season, when surface temperatures were 4–6 °C higher than average and during which 500 billion tonnes of ice vanished. That's 30% more than the previous year, and 4% more than the previous record, set in 2005. “2007 was a shocking year,” says Luthcke. And GRACE's findings are bolstered by observations of dramatic ice losses by other satellites. Radar measurements, for instance, have shown4 that glaciers in southern Greenland are dumping ice into the ocean ever more quickly. At the American Geophysical Union meeting in San Francisco in December, Velicogna presented results showing that the GRACE estimates are supported by data taken from the Ice, Cloud and Land Elevation Satellite (ICESat), which uses a laser altimeter to measure elevation changes on the ice sheet.

An island rising

One reason for needing extra information to supplement the data from GRACE is the problem of "post-glacial rebound." As big as Greenland's ice sheet is today, in the ice age it was just a part of something far bigger, ice that reached as far south as the Ohio Valley and as far east as the Urals. That vast mass pressed the crust beneath it down into the denser mantle below. Although most of the ice has long since disappeared, large parts of the high-latitude crust have yet to recover from this repressed position. Scandinavia, for instance, rises 9 millimetres higher every year as the denser mantle pushes the lighter crust back up. This ongoing bounceback makes analysing the GRACE data harder.

Help may soon come from a system of global-positioning receivers that have just been installed around Greenland to measure how the bedrock is rising over time. Last summer, a team of researchers from the United States, Denmark and Luxembourg put 24 stations around the rocky, ice-free edges of the island — tripling Greenland's global positioning system (GPS) infrastructure in one field season, according to Michael Bevis, the project leader at Ohio State University. The Greenland GPS Network (GNET) is one of the northern components of a two-pole effort called POLENET to measure post-glacial rebound and other phenomena; there will eventually be around 50 GNET stations in Greenland. “We need much improved models of post-glacial rebound, otherwise GRACE measurements will have very limited value in Greenland and Antarctica,” says Bevis. “If we can pull this off, GRACE will become the most powerful system ever devised for measuring ice mass change.”

NASA/GSFC Visualization Studio. Source: S. LUTHCKE.

The GNET stations are strung along the rocky margin of Greenland, mainly in remote areas (see map, above). They require a lot of battery capacity to continue operating throughout the winter months, and links to five of the stations installed last summer have already gone down. The team is planning to retrieve the data manually and fix the stations this summer.

All this makes GNET a fairly expensive proposition. The last field season consumed about US$1 million, and flat budgets, rising fuel costs and the weak dollar are making things even tighter this year. The rest of the GNET stations will have to go in over the next two summers instead of all in 2008, as originally planned.

The GNET receivers are expensive, highly precise, heavy and, in principle, durable. Another monitoring strategy takes the opposite tack; it uses GPS equipment cheap enough to lose, embedded at the calving fronts of some of Greenland's most active "outlet glaciers." These are the thick streams of ice that flow through narrow fjords into the oceans surrounding Greenland. A decade ago, researchers thought that these outlet glaciers moved slowly, creeping downward from the high centre of the ice sheet. In recent years, though, the glaciers have been doing a veritable hokey-cokey on their approach to the ocean, first advancing rapidly, then pulling back.

It started more than a decade ago with the biggest outlet glacier of all, Jakobshavn Isbræ on the west coast, which among its claims to fame is the most likely source of the iceberg that sank the Titanic . Between 1992 and 2003, Jakobshavn Isbræ accelerated from 5.7 kilometres per year to 12.6 kilometres per year5. “That was incredibly dramatic,” says Ian Joughin, a glaciologist at the University of Washington's Applied Physics Laboratory in Seattle. “A decade ago, nobody would have anticipated one of Greenland's biggest outlet glaciers doubling its speed.” Faster glacier movement means more ice dumped into the ocean, and a thinning of the central ice sheet from which the glaciers feed.

Over on the east coast, the island's other two big outlet glaciers also started speeding up6: Helheim in 2002, and Kangerdlugssuaq in 2005. The process didn't go smoothly. Helheim, for instance, retreated more than 3 kilometres between 2001 and 2003 as its front melted away faster than new ice flowed down to make up the difference. Then in 2005 it began advancing again as flow took over. This back-and-forth is captured most dramatically in remote-sensing images from satellites such as NASA's Terra and Aqua. “There is a lot of variability, and the important thing to remember is we only have a few good years of observations,” says Joughin. “We don't know if we are looking at the beginning of a longer-term trend.”

A GPS station, part of a network for measuring crustal movement. M. BEVIS

Joughin and others suspect that the back-and-forth of the outlet glaciers has a lot to do with the geometry of the fjords the ice squeezes through. The glaciers inch forward until their ends finally break off, calving icebergs into the ocean. This relieves stress on the glacier, which begins to surge, much as removing a buttress holding up a rickety old house will cause the house to collapse.

But the scenario is not as clear-cut as it might seem. In the past, glaciers advanced and then calved off icebergs when they got too long. Now, the calving happens while the glacier is advancing. What this means is unclear, but it does suggest that the glaciers are behaving in a fundamentally different manner than just a few years earlier. “This is what we cannot predict,” says Steffen.

But the unpredictable is not necessarily unprecedented. During the 1920s, Greenland experienced a rapid warm-up; average annual temperatures rose more than 2 °C over the decade. At Ohio State, meteorologist Jason Box and student Adam Herrington have been looking for records of what happened to the Big Three outlet glaciers back then, to see whether there are lessons about what to expect in the future. Among their finds was a series of maps showing the snout of the Kangerdlugssuaq glacier. Over just a few years in the early 1930s, the glacier retreated some 10 kilometres upstream — having lost an area up to 70 square kilometres in what may have been a single large calving event. The break-up, says Box, was “exceptional” in that the ice would have taken years to grow back to its previous state. And it suggests that the sort of rapid response to warming seen in recent years is the glaciers' expected response to warming.

One emerging area of research is the effect that ocean temperatures — as opposed to air temperatures — have on the outlet glaciers. Howat says, for instance, that warm ocean temperatures in the summer of 2003 coincided with a time when several of the outlet glaciers feeding into that warmer sea began speeding up dramatically. But little work has been done to correlate ocean temperatures with the glacier retreats. The ocean has been “a total blank spot on the map,” Howat says. “You have a big ice sheet with a lot of it sitting in the water — you'd think you'd want to know what's happening in the water.” Some researchers are starting to target this as their next area of interest.

Lakes on ice

The water that surrounds Greenland has been there forever. More novel is the increasing amount of water which, in summer, sits on top of it. What starts out in the winter as cold white snow ends up in the summer as a landscape of blue water, as more than 1,000 shallow melt lakes up to 5 kilometres across form on the ice. It is like Minnesota — but white.

“You have a big ice sheet with a lot of it sitting in the water — you'd think you'd want to know what's happening in the water.” Ian Howat

2007 was a particularly good year to study this surface melting, because there was a great deal of it. High-pressure weather systems throughout much of the summer kept storms away, allowed the Sun to beat down on the ice almost without cease. The melt season lasted 25–30 days longer than average, and 19,000 square kilometres turned from ice to water, says Marco Tedesco of Goddard — that is roughly the area of Wales. The effect was particularly noticeable at higher elevations; as warm air swept ever higher, the area that melted at 2,000 metres or greater was 150% larger than normal.

Even in a normal May to August field season, researchers have to make sure that their instruments stay anchored on the ice sheet, planting their poles 2–3 metres deep to make sure they can withstand the melt. It's not just the water that makes things difficult — it's the unpredictability. Melt lakes have been known to drain away tens of millions of cubic metres of water in the space of a day, swirling down some unknown drain channel in the ice. Huge waterfalls appear and then disappear overnight. How exactly the water gets from the top of the ice to its bowels isn't known, but understanding the plumbing could help illuminate a crucial question — does the water that reaches the bottom of the ice sheet lubricate it in a way that encourages movement and collapse7? This has become a commonplace speculation among Greenland catastrophists, but the degree to which it is actually happening, how well it explains the ice loss measured by GRACE and to what extent it may change the shorelines of the world is not yet clear.

Back to the Eemian

The suddenly apparent pace of change has led some to question previous, rather staid models of ice-sheet dynamics, which suggest that even fast changes take several centuries. “It has only been in the past five years that we have realized that hey, the ice sheet is falling apart, these changes are happening, our models are way off,” says Howat. But predicting how far off they actually are — and some believe they may not be as soon as catastrophists predict — is not easy. Anecdotes of this or that particular, however momentous, are no match for thorough, consistent monitoring. If you want models of the future you can rely on, you have to monitor the process you model. “The modelling has not happened because there are just not enough data,” says Philippe Huybrechts, an ice-sheet modeller at the Free University in Brussels. Researchers on the ice might see moulins forming, or outlet glaciers calving, but “it is just in one place and for one season, or for a few weeks,” he says. “To generalize from that over a whole ice sheet in a way that you can predict things, it's just not possible.”

At the moment, the best Greenland modellers are stretched by trying to explain what has already happened, without even thinking about what is to come. They are responsive, not predictive. But some are trying to change that. At the University of Kansas, Cornelis Van der Veen is helping to lead an effort to improve ice-sheet models; he and others are planning a major conference to be held in July in St Petersburg, Russia. The idea is to identify the big unknowns and figure out how to tackle them, one by one. “One outlet glacier speeding up isn't really the end of the world,” he notes. “But if they are doing that all over the place then that is an indication that something is going on that we really do not understand. It is not something that can be solved within a couple of months.”

The calving rate of some Greenland glaciers has increased. J. BALOG/AURORA PHOTOS

“It's very difficult to model a new process, such as why glaciers accelerate, before you have an understanding of why it is happening,” says Dorthe Dahl-Jensen of the University of Copenhagen. “One thing is to observe it. The next step is to understand it. The third is to put it into the model and predict the future. We are at step two, struggling to understand the process.”

One route to understanding may be through palaeoclimate studies. Dahl-Jensen is leading a team that aims to drill a core 2,500 metres into the ice of northwestern Greenland over the next couple of summers. This core — the North Greenland Eemian Ice Drilling — would complement the pioneering climate records cored out of Greenland's ice over the past couple of decades. None of the earlier cores was able to extract an unbroken record of the Eemian stage, some 120,000 years ago and the last time that Earth was in a warm "interglacial" period. Understanding what Greenland was like then could help scientists understand how the ice sheet might respond in a warmed future, says Dahl-Jensen. Temperatures in Greenland were roughly 5 °C higher during the Eemian than they are today. Yet sea level was only one or two metres higher, and every ice core that has ever been drilled deep enough on the island has included some ice from the Eemian. “A major part of the Greenland ice sheet survived,” says Dahl-Jensen — and argues that more sampling of this period might help to pinpoint the factors that could allow ice to stick around when temperatures are higher than today.

“Every summer brings something totally different.” Leigh Stearns

But this is not necessarily the encouraging news it might seem. Because global warming is amplified near the poles, 5 °C of warming in Greenland might be achieved with just 2.5 °C of average global warming — which is quite plausible. And an important regional factor here might be the dramatic recent reductions seen in the sea ice to the island's north. The extent to which the cold, reflective ice on the sea keeps Greenland cool is simply not known.

The long view needed

More sampling of the past, together with that of the present, may help us to unravel the future of the Greenland ice sheet. For now, though, things seem to be getting more ravelled, not less. Every year brings a new set of data, a new insight into the behaviour of Greenland's interlocking ice-sheet dynamics, stream flows and glacial surges. “We are just learning so much,” says Leigh Stearns, a glaciologist at the University of Maine at Orono. “Every summer brings something totally different.”

Melt water draining into moulins could accelerate the movement of the ice sheet. I. JOUGHIN

But if the learning is copious, it is not systematic. Despite the real risk of a meltdown — and the real benefits to be gained from being able to say something reliable about how long there is to go, and how high the seas might rise — the investigation of the ice's every nook and cranny is far from over. One idea is to use unmanned aerial vehicles (UAVs) to fly across the ice sheet gathering data such as the depths of melt lakes. But this is easier said than done; John Adler, a PhD student at the University of Colorado at Boulder, ran some tests last August in which he took three types of commercially available UAVs to Kangerlussuaq airport and ran flights over the melt lakes for a week. He is still getting the kinks out of the system, but says that UAVs could provide a cheaper and more repeatable way to get local measurements than relying on expensive helicopter flights, as is done today. Even so, the UAVs are labor intensive and cannot be operated all year round.

Over the long term, satellites should provide the most coherent record of change. The Terra and Aqua satellites, along with Europe's Envisat and other surface-monitoring satellites, are workhorses that regularly photograph the advance and retreat of outlet glaciers. Despite its glitches, the ICESat altimeter sends back elevation changes that track the thinning of the ice sheet; a successor, ICESat-II, is already in the works. And the European Space Agency is working to launch a successor to the ice-thickness-measuring CryoSat, the first incarnation of which failed after launch in 2005.

Yet major problems remain in acquiring and using Earth-observation data (see Nature450, 782–785; 2007). Access to data from Canada's Radarsat-1 and Radarsat-2 for instance, is ensnarled in a potential takeover by a U.S. company, a sale that was blocked last week by the Canadian government.

Even with the right satellites, not everything can be done from space. Yet very few researchers have Greenland as the main focus of their scientific work. Decades from now, this could turn out to be one of the most short-sighted allocations of resources that began the twenty-first century. Climate change elsewhere in the Arctic has been swifter than anticipated. The remarkable shrinkage of the sea is “the largest change in Earth's surface that humans have probably ever observed,” Howat points out. Trying to get any and every handle on how that affects the poised mass of ice next door must surely be a priority, he says. “This should be a critical thing to study.”